Add basic SparQL queries to competency-questions file

[romainsacchi]

For users not so familiar with SparQL and querying triples, it would be nice to have documented simple queries like:

• [ ] for how many regions are there data sets for activity X?
• [ ] what is the activity type of activity X?
• [ ] what is the output of activity X the input of?
• [ ] what is the original data source for activity X?
• [ ] what are the first degree inputs for activity X?
• [ ] how to extract a list of available impact assessment methods?

Etc... @kuzeko

[kuzeko]

@IKnowLogic can we copy somewhere here the queries from Yasgui?